The invention relates to a microporous insulation containing one or more ingredients which undergo phase transitions as the temperature of the microporous insulation is raised and, in particular, to such an insulation material that is suited for use in shielding flight data and voice recorders from fires and high temperature environments.
There are numerous insulating applications, such as, fire safes, cable trays and fire walls where it is desirable or necessary to insulate and protect items, devices, assemblies and/or areas from high temperature environments or fire. One very important insulating application is the insulation and shielding of flight data and voice recorders from the high temperature environment and fire frequently present after an aircraft has crashed. U.S. Pat. No. 4,694,119; issued Sep. 15, 1987; and entitled "Heat Shielded Memory Unit for an Aircraft Flight Data Recorder", discloses an insulating system in which a layer of wax encapsulates the recorder and, in turn, is enclosed within a thermal liner of MIN-K 2000 insulation or a similar insulation liner. At a certain temperature the wax undergoes a phase transition and functions as a heat sink to keep the temperature of the recorder below a certain critical temperature.